Decoupling wave field microseism inverse time interference positioning method

Abstract

The invention discloses a decoupling wave field microseism inverse time interference positioning method. The method comprises the following steps: performing the decoupling of wave field in anisotropic medium for each time step length by continuation time of the wave field inverse time; taking self-correlation and mutual-correlation of the decoupling wave field as an imaging condition, performinginverse time interference positioning; increasing the focusing of the inverse time interference positioning image in the anisotropic medium, and pressing imaging illusion, thereby improving the positioning precision. The wave field in inverse time propagation of the anisotropic medium is decoupled at each time step length, the inverse time interference positioning is performed by utilizing the mutual-correlation imaging condition of a P wave field and S wave field, a seismic focus location can be obtained, the radiation petal pattern of seismic source energy can be obtained, thereby qualitatively judging the seismic source radiation characteristic, and laying basis for the inversion of a seismic source mechanism.

Description

technical field [0001] The invention relates to a microseismic positioning method, in particular to a decoupling wave field microseismic reverse time interference positioning method, which belongs to the technical field of microseismic monitoring. Background technique [0002] In recent years, microseismic monitoring technology has been widely used in hydraulic fracturing monitoring of tight oil and gas reservoirs, mine rockburst monitoring, carbon dioxide geological storage monitoring and conventional oil and gas field injection-production induced seismic monitoring. Especially in the development of tight oil and gas reservoirs, microseismic hydraulic fracture monitoring is the only far-field technique capable of imaging induced fracture geometry. By real-time microseismic monitoring of the time and space distribution of the source, the geometric occurrence of the induced fracture, the change of the ground stress and the connectivity of the fracture grid can be estimated, s...

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Problems solved by technology

[0024] From Figure 2(b), it can be seen that the reverse time wave field fails to focus at the source

[0025] (2) When the wave field is extended backward in an anisotropic medium, different seismic phases are coupled together, and the energy of the wave field interferes with each other and superimposes, resulting in strong imaging artifacts that interfere with the determination of the real source location

[0028] It can be seen from Figure 3(b) that in addition to shallow imaging noise, there is strong sidelobe interference near the real source, which shows that it is difficult to obtain satisfactory positioning results using coupled wavefields for reverse time interferometric positioning in anisotropic media

[0029] (3) At present, the conventional reverse time interferometry method can only give the location of the seismic source, but cannot provide characteristic analysis from the radiation characteristics of the seismic source

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